416 DESCRIPTION OF [Rotatoria. 



so that, in a physiological sense, there is no lens or 

 cornea. B. pala, urceolaris, and rubens, sometimes increase 

 in such quantities as to render the water milky and turbid. 

 Several species are infested with Vorticellae, Epistylis, and 

 other parasites, which attach themselves to their shells. 



721. BRACHIONUS pala. The four-horned Brachionus 

 has a smooth lorica, with four teeth or spines in front, and 

 two obtuse ones near the opening for the foot. This 

 creature swims in a perpendicular position, the brow being 

 directed upwards. Each jaw has five teeth ; the alimentary 

 canal, being restricted, forms a stomach. Length l-36th; 

 lorica only l-48th. 



722. BRACHIONUS amphiceros. The double four-toothed 

 Brachionus has a smooth lorica, with four spines, both in 

 front, and posteriorly. This species may be distinguished 

 from the preceding by its size, want of frontal seta?, and 

 by the four sharp posterior teeth. Length l-72nd. 



723. BRACHIONUS urceolaris (Brachionus urceolaris., M.) 

 The urn-shaped Brachionus is whitish, has a smooth lorica, 

 six very short spines in front, the posterior extremities 

 rounded. The points of the lorica are shorter and less 

 sharp than in the following species ; its lorica is slighty 

 granulated ; delicate longitudinal ridges proceed from the 

 spines; the jaws have each five teeth. Both sexual glands 

 and contractile vesicle, as well as an ovarium, are seen. 

 Found in fresh and brackish water. Length l-96th to 

 l-72nd. 



724. BRACHIONUS rubens (Brachionus urceolaris^ M.) 

 The reddish Brachionus has a smooth lorica, with six sharp 

 spines in front, and posterior rounded ; the body is red. 

 Length l-50th. 



